Might be a stupid question, but is this shoe breathable? Also general consensus is to size down? Is that true even if I choose to wear dress socks with these?

I don't blame you for asking this question, but I will point out that there a 181 pages of Clarks DB sizing questions. With that said size down a 1/2 from your measured shoe size. I'm a 10 and wear a 9.5. They fit perfect. I can wear them with thick, medium, and no socks.